The basic idea is to create a homogenous phage hemagglutination assay (HPA-homogeneous phage agglutination) for the rapid diagnosis of HIV infection. The design employs M13 phages displaying two different molecules on their surface, an antibody or other binding site able to react with a conserved cell surface marker of human erythrocytes (e.g., glycophorin A), fused to protein 3, and an antigen representative of a human infectious agent, fused to protein 8. In phase I, we created and validated this assay using an HIV-1 gp41 peptide with proven diagnostic value. Recombinant phage particles placed in direct contact with red cells and a positive control antisera induced erythrocyte agglutination indicating that the anti-HIV antigen antibodies present in the serum bridged the phage particles attached to different red blood cells. Importantly, negative control antisera did not show agglutination. Based on these positive results, the goals of phase II are to 1) Optimize the assay using human sera panels and/or blood from infected individuals; 2) Scale-up the diagnostic phage particles, and prepare a clinical prototype diagnostic reagent kit ; 3) establish assay variability, quality control, etc. Finally, we will evaluate performance of this Rapid HIV Homogeneous Phage Assay on clinical samples in collaboration with the Division of AIDS, STDs and Tuberculosis Laboratory Research at the CDC. PROPOSED COMMERCIAL APPLICATIONS: Development of a rapid HIV homogeneous assay will have significant commercial potential for the field and office diagnosis of HIV.